watchOS 5.1 (build 16R5589c) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2018-10-22T17:19:39Z. The update package is 404.97 MB. This is a delta (partial) update that requires 5.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8b8f36d44ba7d72cb99bbc3663e3e847c321f198.zip.